a) Field of the Invention
The present invention relates to a multi-cell battery structure applicable to an electric vehicle or hybrid vehicle, viz., an electric motor powered vehicle.
b) Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 9-86188 published on Mar. 31, 1997 which corresponds to a U.S. Pat. No. 5,866,276 issued on Feb. 2, 1999 exemplifies a previously proposed battery structure for an electric vehicle (EV).
It is a general practice that, in a case where a large capacity of the battery is used in the electric vehicle, a plurality of cells are connected partially in parallel to each other or connected in series with each other to form a battery.
In the battery cell structure disclosed in the above-described United States Patent, eight cells are housed in a battery casing to form a cell group of battery. Bus bars (so-called, high power system wires) to be caused to flow electric current outputted from the battery to drive the vehicle are disposed within a battery casing.
On the other hand, a cell controller is used to control the battery so as to make states (charge and discharge states) of each cell to form the battery equal to each other. Signal transmitting wires (low power system wires) are distributed between the battery and the cell controller. The signal transmitting wires include cell terminal voltage measuring wires, control-purpose wires, and wires connected to a sensor to detect a temperature of the battery.
However, since, in the previously proposed battery cell structure disclosed in the above-described United States Patent, the battery is constituted by a relatively small number of cells so that no special consideration of wiring method (how to distribute the wires in the casing) for the low power wirings and the high power wirings in the casing is taken into account.
However, as the number of battery cells to form the battery are increased, the number of wires are increased in the battery casing and lengths of the respective wires themselves are increased.
Consequently, together with complicated wirings within the battery casing, the signal transmitting wires become susceptible to the high power of the bus bars. In addition, mutually adjacent wires wear out due to the vibrations during the run of the vehicle.
It is, hence, an object of the present invention to provide a multi-cell battery which can prevent a physical interference between the bus bars and the signal transmitting wires and which can have a good wiring operability.
The above-described object of the present invention can be achieved by providing a multi-cell structure battery, comprising: a plurality of cylindrical cells accommodated in a casing; bus bars to connect respective terminals of the cells; signal transmitting wires to connect the respective cells to an external device; a cell holder to hold the cells; and a covering fixed to the cell holder so as to oppose against the terminals of the cells, the bus bars being disposed on an inner surface of the covering opposed to the terminals of the cells and the signal transmitting wires being disposed in an outer surface of the covering.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.